<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    let hd = [];
    let hdcms = {};
    console.log(typeof hd)
    console.log(typeof hdcms)
    //发现， hd 和 hdcms都是object 类型，不能进一步判断

    //进一步使用instanceof 判断是不是数组

    console.log(hd instanceof Array)//true

    console.log(hdcms instanceof Array)//false
</script>
</body>
</html>
